1. Technical Field
The present invention relates to a method for manufacturing a MEMS device including a wiring covering a resin and the surface of the resin as, for example, bump electrode and a method for manufacturing a liquid ejecting head.
2. Related Art
A micro electro mechanical systems (MEMS) device which includes a bump electrode electrically connecting between two substrates is applied to various apparatuses (for example, liquid ejecting apparatus, sensor, or the like). For example, a liquid ejecting head which is a type of MEMS device includes an actuator such as the bump electrode described above and a piezoelectric element and transmits a driving signal (electrical signal) to the actuator via the bump electrode. In addition, as the liquid ejecting apparatus on which such a liquid ejecting head is mounted, for example, there is an image recording apparatus such as an ink jet type printer and an ink jet type plotter. In addition, recently, the liquid ejecting head having a feature that a very small amount of liquid can be accurately landed to a predetermined position is developed and then is also applied to various manufacturing apparatuses. For example, the liquid ejecting head is applied to a display manufacturing apparatus for manufacturing a color filter such as a liquid crystal display, an electrode forming apparatus for forming an electrode such as an organic electro luminescence (EL) display and a face emitting display (FED), and a chip manufacturing apparatus for manufacturing a biochip (biochemical element). Liquid ink is ejected from a recording head for the image recording apparatus and a solution of each color material of red (R), green (G), and blue (B) is ejected from a color material ejecting head for the display manufacturing apparatus. In addition, a liquid electrode material is ejected from an electrode material ejecting head for the electrode forming apparatus, and a solution of a biological organic material is ejected from a biological material ejecting head for the chip manufacturing apparatus.
As the bump electrode, there is a bump electrode provided with a series of resin portions (resin layers) formed on the surface of the substrate and a wiring formed on the resin portion (see, for example, JP-A-2009-260389). Here, in a portion of the resin portion corresponding to space between adjacent wirings (that is, between the bump electrodes), the portion of the surface thereof is partly scraped by etching and becomes small. In other words, the height of the resin portion (dimension from substrate to upper surface of resin portion) between the adjacent wirings is formed to be lower than the height of the resin portion (that is, resin portion at portion covered with wiring) positioned immediately under the wiring (see, JP-A-2009-260389). Such a shape is formed by forming a wiring on the resin portion, using the wiring as a mask, and then etching the resin portion.
Here, in the etching of the resin portion, even if dry etching is used, the resin portion positioned immediately under the wiring is side-etched. In other words, as illustrated in FIG. 19, when a resin portion 91 formed on a substrate 90 using, for example, oxygen plasma is etched, the side surface of the resin portion 91 where the oxygen plasma is positioned immediately under a wiring 92 is slightly scraped. Therefore, the width of the resin portion 91 positioned immediately under the wiring 92 is smaller (thinner) than the width of the wiring 92 covering the resin portion, and a portion of the wiring 92 protrudes to the outside of the resin portion 91. As a result, for example, in a case where the resin portion 91 is pressed in a direction to crush so as to connect the wiring 92 of the bump electrode 93 to the terminal formed on the opposing substrate thereof, there is a fear that the bump electrode 93 is inclined or fallen down and shape thereof may collapse. When the shape of the bump electrode 93 collapses, the reliability of the electrical connection is reduced. The broken line arrows illustrated in FIG. 19 represent the flight images of the oxygen plasma.